INFLUENCE OF PRESSURE OSCILLATIONS IN COMMON RAIL INJECTOR ON FUEL INJECTION RATE

Fuel injection causes considerable oscillations of fuel pressure at the injector inlet. One of the reasons is hydraulic impact when the needle valve closes. For multiple injections, the previous injections affect the following. As both the fuel pressure in rail pac and the injection rate grow, the oscillations increase. The pressure oscillation range at the common rail injector inlet at pac=1500 bar is up to 350 bar, and at the rail pressure pac=500 bar, the amplitude decreases to 80 bar. Physical properties of the fuel are also important. As the viscosity of the fuel increases, its hydraulic friction grows which results in a rapid damping of pressure oscillations. The data for an injector operating on sunflower oil is presented. As compared with diesel fuel, the oscillations range decreases from 400 to 250 bar at the same operating mode. The influence of the interval between the impulses of a double injection on the injection rate of the second fuel portion was investigated. Superposition of two waves during multiple injections may result in amplification and damping of the oscillations. Simulation was performed to estimate the influence of fuel type and time interval Δτ between control impulses of a double injection on the injection quantity of the second portion at pressures of 2000-3000 bar. When the rail pressure pac grows, the oscillations and their impact on the injection process increase. For diesel fuel at pressure of pac=2000 bar, the variation in injection rates of the second portion is 2.36-4.62 mg, and at pac=3000 bar – 1.58-6.63 mg

Simulation of fuel injection through a nozzle having different position of the spray holes

In the article, a method of hydraulic calculation of working process of a diesel fuel feed system having a nozzle with different positions of its spray holes was investigated. A research of diesel engine injector nozzle design which had two groups of holes was carried out. Entering edges of the first group with the coefficient of flow μhl were located in the sack volume and entering edges of the second group (coefficient of flow μhu) – on the locking taper surface of the nozzle body. The coefficients of flow μhl and μhu differ considerably and depend on the valve needle position. This enables to distribute rationally the injection quantity by injection holes taking into account operating conditions of the diesel engine and hence – by the combustion chamber zones

Results of simulation and experimental research of automobile gas diesel engine

The paper is dedicated to conversion of a truck diesel engine into a gas diesel engine. Different ways of diesel engine conversion for operation on natural gas were analyzed. The gas diesel working process with minimized portion of igniting diesel fuel supplied by the Common Rail system was selected as the most suitable for such an engine. Modular gas feed and electronic engine control systems were developed in MADI which may be mounted on high- and medium-speed gas diesel engines. The fuel supply system of the base diesel engine was preserved though a new algorithm of fuel injection for the gas diesel engine was developed. The systems were perfected using simulation by computer model developed in MADI and during engine tests. The gas diesel engine demonstrated good fuel efficiency and considerable decrease of NOx and CO2 emissions, though its power at low speed decreased compared to the base diesel engine. The ways to improve this drawback during the future work were proposed

The economic approach to designing anticorruption institutions

Contemporary economic analysis of corrupt behaviour requires practical consideration of the issues concerning projecting of social anti-corruption institutions. The economic science has accumulated sufficient practical experience of institutional construction in society, for instance approaches provided by K. Sunstein’s and E. Ostrom. The requirement of reasonability in managing economic interactions makes the society refuse from the dichotomy of market (anarchical, spontaneous) and non-market (hierarchical) institutions. The same tendency can be observed in arranging anti-corruption struggle in state management. Both approaches - aimed at creating fixed vertical hierarchy as well as at creating competition at the lowest bureaucratic level - are inappropriate. That is why anticorruption institutions arranging should be based on economic models of rational criminal and citizens involvement in law enforcement activity. These models enable to harmonize state dirigisme related to the state management ex ante with basic provision of laissez-faire doctrine – personal motives of people’s behaviour. Standard economic supply and demand model has shown inelasticity of corruption crimes supply in Russia. Non-price determinants (cultural norms, “tabu”) seem to be more significant in motivating corruption behaviour than price determinants (seriousness and probability of punishment). Economic characteristics of elasticity and inelasticity of supply and demand in the model of involvement into law enforcement activity enable to create strategy of developing social anti-corruption institutions

Mechanism of Water Intrusion into Flexible ZIF-8: Liquid Is Not Vapor

Zeolitic Imidazolate Frameworks (ZIF) find application in storage and dissipation of mechanical energy. Their distinctive properties linked to their (sub)nanometer size and hydrophobicity allow for water intrusion only under high hydrostatic pressure. Here we focus on the popular ZIF-8 material investigating the intrusion mechanism in its nanoscale cages, which is the key to its rational exploitation in target applications. In this work, we used a joint experimental/theoretical approach combining in operando synchrotron experiments during high- pressure intrusion experiments, molecular dynamics simulations, and stochastic models to reveal that water intrusion into ZIF-8 occurs by a cascade filling of connected cages rather than a condensation process as previously assumed. The reported results allowed us to establish structure/function relations in this prototypical microporous material, representing an important step to devise design rules to synthesize porous media

Perylene Diimide as a Precise Graphene-like Superoxide Dismutase Mimetic

Here we show that the active portion of a graphitic nanoparticle can be mimicked by a perylene diimide (PDI) to explain the otherwise elusive biological and electrocatalytic activity of the nanoparticle construct. Development of molecular analogues that mimic the antioxidant properties of oxidized graphenes, in this case the poly(ethylene glycolated) hydrophilic carbon clusters (PEG–HCCs), will afford important insights into the highly efficient activity of PEG–HCCs and their graphitic analogues. PEGylated perylene diimides (PEGn–PDI) serve as well-defined molecular analogues of PEG–HCCs and oxidized graphenes in general, and their antioxidant and superoxide dismutase-like (SOD-like) properties were studied. PEGn–PDIs have two reversible reduction peaks, which are more positive than the oxidation peak of superoxide (O2•–). This is similar to the reduction peak of the HCCs. Thus, as with PEG–HCCs, PEGn–PDIs are also strong single-electron oxidants of O2•–. Furthermore, reduced PEGn–PDI, PEGn–PDI•–, in the presence of protons, was shown to reduce O2•– to H2O2 to complete the catalytic cycle in this SOD analogue. The kinetics of the conversion of O2•– to O2 and H2O2 by PEG8–PDI was measured using freeze-trap EPR experiments to provide a turnover number of 133 s–1; the similarity in kinetics further supports that PEG8–PDI is a true SOD mimetic. Finally, PDIs can be used as catalysts in the electrochemical oxygen reduction reaction in water, which proceeds by a two-electron process with the production of H2O2, mimicking graphene oxide nanoparticles that are otherwise difficult to study spectroscopically

Mechanistically-guided materials chemistry: synthesis of new ternary nitrides, CaZrN2_2 and CaHfN2_2

Recent computational studies have predicted many new ternary nitrides, revealing synthetic opportunities in this underexplored phase space. However, synthesizing new ternary nitrides is difficult, in part because intermediate and product phases often have high cohesive energies that inhibit diffusion. Here, we report the synthesis of two new phases, calcium zirconium nitride (CaZrN$_2$) and calcium hafnium nitride (CaHfN$_2$), by solid state metathesis reactions between Ca$_3$N$_2$ and $M$Cl$_4$ ($M$ = Zr, Hf). Although the reaction nominally proceeds to the target phases in a 1:1 ratio of the precursors via Ca$_3$N$_2$ + $M$Cl$_4$ $\rightarrow$ Ca$M$N$_2$ + 2 CaCl$_2$, reactions prepared this way result in Ca-poor materials (Ca$_xM_{2-x}$N$_2$, $x<1$). A small excess of Ca$_3$N$_2$ (ca. 20 mol\%) is needed to yield stoichiometric Ca$M$N$_2$, as confirmed by high-resolution synchrotron powder X-ray diffraction. In situ synchrotron X-ray diffraction studies reveal that nominally stoichiometric reactions produce Zr$^{3+}$ intermediates early in the reaction pathway, and the excess Ca$_3$N$_2$ is needed to reoxidize Zr$^{3+}$ intermediates back to the Zr$^{4+}$ oxidation state of CaZrN$_2$. Analysis of computationally-derived chemical potential diagrams rationalizes this synthetic approach and its contrast from the synthesis of MgZrN$_2$. These findings additionally highlight the utility of in situ diffraction studies and computational thermochemistry to provide mechanistic guidance for synthesis

THE POSSIBILITIES OF DEVELOPMENT OF THE ELECTRONIC OGE-SPECTROSCOPY: THE COUNT OF THE SURFACE ROUGHNESS INFLUENCE AND THE RESTORATION OF THE SPECTRES FORM

The object of investigation: emission of the oge-electrons from the rough surface and the process of treatment of signal in the oge-spectroscopy. The purpose of the work: rise of the information validity, to be received with the aid of the electronic oge-spectroscopy. The theoretical model of influence of the surface roughness on the oge-signal has been built, the possbility of restoration of the differential form of the oge-spectres without measuring the analyzer hardware function has been proved. The methods of count of the specimen surface roughness, smoothing and restoration of the spectre form with the performance of the oge-analysis have been developedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio